Heating system control



. E. c. AVERY ETAL Re. 21,969

HEATING SYSTEM CONTROL I Original Filed July'16, 1938 INVENTDRS FRED H. BLEASIJH EDWARD lLAvERY ATTORNEY Reissued Dec. 9, 1941 UNITED STATE Edward Serial 2 Claims.

This invention relates to improvements in controls for heating systems, and is more particularly concerned with a control for a domestic heating system employing an automatic coal stoker of the type having two rates of feed or operation, a low rate of feed when the dwelling thermostat is satisfied and a high rate of feed when the dwelling thermostat is calling for heat. Domestic heating systems of the foregoing type are in common use today, and in them the automatic stoker runs continuously throughout the heating season, either at the high rate of feed or at the low rate of feed, depending upon the condition of the dwelling thermostat or thermostats. One of the better known automatic stokers of this type, and to which the control system of our invention is particularly although not exclusively applicable, is sold under the trade name Electric Furnace Man. With such systems, on mild days in spring and fall, the dwelling frequently becomes overheated because of continuous operation of the furnace, which term is used herein generically to include a hot air fur nace, boiler or other domestic heating plant, at the low rate of the feed of the Stoker.

The principal object of our invention is to provide a control for a heating system of the type described which will overcome the disadvantage just mentioned and effect a saving in fuel con sumption, and which is simple in construction, and positive and efficient in operation.

More specifically, it is an object of our invention to provide a dual control for the fuel feeding mechanism of a stroker fed furnace of the type described, whereby the stoker will be operated at the high rate of feed when the dwelling thermostat is calling for heat, and when the dwelling thermostat is satisfied, the stoker will be operated intermittently on a predetermined time schedule at the low rate of feed, which time schedule may be so selected as to be just capable of maintaining the fire to prevent its extinguishment.

Other objects and advantages of this invention will be apparent from the following description when taken in connection with the accompanying drawing, in which:

Figure 1 is a diagrammatic view showing a stoker fed furnace with our control system applied thereto.

Figure 2 is a diagrammatic view showing parts of our control system, including timing mechanism for controlling the intermittent operation of the stoker at the low rate of feed when the dwelling thermostat is satisfied.

5 {PATENT osrlce 21st!) HEATING SYSTEM CONTROL 0. Avery and Fred H. Gleason, Auburn, N. Y., assignors to Gleason-Avery, N. Y., a corporation of New York Original No. 2,147,231, dated February 14, 1939,

No. 219,554, July for reissue December 2'7,

Inc., Auburn,

16, 1938. Application 1939, Serial No. 311,211

The control system of our invention is adapted to control the operation of a stoker, generally indicated by the numeral H, which feeds fuel to a furnace generally indicated by the numeral l2. While the control system of our invention may F be used to regulate the operation of other types of stokers, it is, as stated above, particularly adapted for use in connection with that type of domestic stoker known as the Electric Furnace Man.

In general, the stoker may comprise a housing l3 which encloses the driving mechanism for the stoker and to which coal is fed preferably by a screw conveyor extending into the coal bin. From the housing l3 the fuel is fed through a tube by a screw conveyor to the fire pot in the furnace.

The stoker feed regulating arm I6 is connected by a cord or chain I! to a pivotally-mounted control arm l8 operated by a control motor l9,

" which in turn is actuated in accordance with the condition of a thermostat 2|. The control motor l5 and the thermostat 2| have been shown only diagrammatically, since they constitute no part of our present invention and standard mechanisms of the type required are well known in the art to which this invention applies. It is suilicient to state that the in the rooms to be heated, is adapted to cause operation of the control motor l9 in accordance with the heat requirements of the rooms. The control motor l9 operates the control arm l8 and thereby moves the feed regulating arm Hi from the low fuel feed positions, illustrated in Figure 1, to a high fuel feed position in which the arm I6 is moved upward from the position shown in Figure 1. It will be understood that the arm I5 is in the low feed position when the thermostat 2| is satisfied, andis moved to the high feed position when the thermostat 2| is callingfor heat.

The thermostat 2| is conveniently positioned in the dwelling or other building at a point where the temperature maintained will more or lesscontrol the temperature throughout the building or, if desired, individual thermostats can be placed in the separate rooms and additional mechanism provided to enable heat to be supplied tothe room desired in accordance with practices well known in the art. For the purpose of the present invention, a single thermostat will suffice to illustrate the operation of our control system.

The parts so far described are conventional in under consideration,

heating systems of the type thermostat 2| mounted and the electric motor which drives the stoker slowly. The shaft 5! is mounted on a bracket 6| would ordinarily be connected directly to the pivoted on the shaft 60 to swing about said shaft power lines so as to be running continuously as an axis. The bracket 5| also carries a shaft throughout the operation of the heating system. 62 upon which is mounted a gear 63 and a. pinion According to our invention, however, we intro- 5 64. The bracket 6| has an arcuate slot 65 with duce additionalcontrols which will- -now-be dewhich iswadapted. to register. a thumb screw 66 scribed. which extends into the mounting plate.

The arm I8 is adapted to operate, through a The face of the gear 59 has two Se of upulley and c rd assembly 22, a it h lever 23.. ations, as shown, the graduations indicating min which projects from a housing 24. The housing 10 utes. On the shaft 60 is mounted a cam 61. On 24 contains the timing mechanism of our invena s a tiai xtending through a bore in shaft 60, tion which is illustrated in Figurez, and al1-of the s rnounted a second cam 69. The cams 61 nd parts shown in Figure 2 are inpractice-=mounted 9," oth of whichare-driven by th Shaft are within the housing 24 except the stoker motor engaged by Tsp'rl'ng arms 79 d respectively- 25, the manual switch 26 and the limit switch 21, e Sp ing arms 10 and H are suitably mounted the functions of which will hes-pointed out hereI- rig' Suppo t indicated at 12, and inafter. Leads 28 and 29 suppiytelectric power; a yc t i d The spring a 0 and usually from a 110 volt so cycle alternating cur- Tl Wlth their Contact 73 d comprlse e mt source, to the control System actuated switch 56 previously mentioned.

Referring now more particularlyto Figure2, o 93 P I theshaft 15 a hu b Wheel power supply leads 28 and 29"are connected'to w 5 Connected m UD terminal post's 30 and 3 locatedwithin the: housing 24; Asynchronous motor '33, which'drives: the timing mechanism, is-conne'cted across the. I I I I I I terminals n Bland The sprmgarm l0ridesonthe 1owpo1ntof the cam 61 stoker motor 25 is connecte'dto terminal. posts I I I I I as and'31by leads, as and '39,and thelimit switch the'cam 691th? Contacts n I m 21' isconnected to terminal postsj lll and 4| by leads 4! and'43jall ofthese terminals beinglikewiselocated within the housing 24. Terminal 30' posts. 3| and"36,f and'31 and 40', respectively, are connected together by. tieba'rs', as. illustratedf Th switch lever. 23,.servestooperate anormali for'lwhmh'theipomter been Set"- With' the setting shown in Figure 2'; the .stoker motorisicperated'on a-sixty minute cycle,- in such manner that: the. stoker motor will be operated four minutes-in everysixt-y minutes. When the A. I 1 1], thumb scre.w 66 isir loosened-zand therbracket" 54* switch is provided with two terminals 46 and I I I I I fli wliioh"are'corinected across the terminal posts I -S'W1{ngamund It-S'piYOt to the dotted hne posmon 38' andf4j| byle'a'ds 48 and; A cam actuated 40' switch 50which is controlled through "a'timilig t t n' the F F Q t 33 The motor is then o erated on: a'thirty minute n ,p m, described 1 t E cycle; so that; with the-setting of the=pointer 16 nected across the terminal posts 30 and 4| by leads il and'52 and hence. is in parallelfwith'the 45 switch 45. The manual; switch 2.6 is also con- It thus apparent, that with, time.

ne'cted'acrossthe-terminal posts 30 and' ll. I I I v Itvwilli be' seen from the; foregoing that the. control desmbed and with themanualswmhli f tenth-ititai s?assistants of 11 the stoker operates in the customary mannerjof mostat Setting; Should thefithermostat H n the-prior art the rateof'feed ofthe stoke'r be- I I I. I I for heat the arm I8 W11 lng'controlled by the thermostatil; controlmo- I I tor"|9="andff'ed' regulatih'g 'arm -l6" as'de'scrihe tg2w1gih ithrough. the pulley'and above: When the manual switch ifi' is op i motor. circuit through.thesWitCh-AS to operate the f ifi .l i q fi f i'i m P fi Y f stoker continuously at the highlfuel feederate. PP i ,P 1 h? 9 l P control system: dictated by the correspondingmpper position of andwemes as-descrlbsd below? the. arm- |.6, untill'the demand for. heat by the.

Acco ding t 'i t e synchronlous therniostat'is satisfied. The arm |8 will then 0 T3 d S'a D Q' ich nu n v swing. back to its original position lowering. the a "gear;56 'on' ashaft"5|.. On the shaft 51. is also arm |6.,,and1 the arm. 23,-. and the stoker motor mounted a pinion 58JWhich meshes'with a gear, circuit, will be. broken at'theswitch 45, andthe 59.n'1ounted on a shaft 6!! carried by amounting stolter" motor operated intermittently. by the. p1ate-(not: shOWn)-.. here isthus accomplished a. t. switch 50' and he m am hanis'm as above speedreduction' so "that "the"sh'aft 60 is 'driven" described.

It will be particularly noted that the stoker motor may be operated continuously during periods of cold weather by closing the manual switch 26, so that the stoker will feed fuel continuously either at a high feed rate or at a low feed rate, depending upon the demands of the thermostat 2|. When the weather is warm, as in the spring and fall, the manual switch 26 may be opened, and the starting and stopping of the stoker motor will be under the control of the timing mechanism except when the thermostat 2! calls for heat.

The system may, if desired, be operated throughout the entire heating season under the control of the timing mechanism, and this we have found to be the most economical operation, as even during periods of relatively cold weather there are times when for several hours the thermostat will not demand heat, and a considerable saving in fuel is effected by operating the stoker motor merely intermittently to supply sufficient fuel to prevent extinguishment of the fire. Only a slight amount of experimenting is required to ascertain the proper setting of the pointer 15 and the bracket El, so that sufiicient fuel is fed to the furnace to prevent extinguishment of the fire.

It will be apparent that various changes in the form and relation of the parts of our invention may be made without departing from the spirit of the invention as set forth in the appended claims.

We claim: I

1. An interval timer for a thermostatically controlled, electric motor-driven stoker of the type having a variable feed rate, said thermostatic control including means for obtaining a high rate of feed when the thermostat demands heat and a low rate of feed when the thermostat is satisfied, comprising in combination, a switch adapted to be connected in the stoker motor circuit and adapted to be closed when said thermostat demands heat, a synchronou electric motor, a speed reducing mechanism driven thereby, means for selectively varying the speed reduction effected by said mechanism, a shaft driven by said speed reducing mechanism, two cams mounted on said shaft for rotation therewith, means for changing the relative positions of said cams with respect to each other, and a second switch in parallel to said first switch and having two arms each operated by one of said cams, whereby said second switch will be closed for such part of each revolution of said shaft as may be determined by the setting of said cams.

2. A stoker control system for maintaining a fire by means of timed periodic operation at a low rate of feed of the stoker in a heating system comprising a furnace, an electric motor and a motor circuit for operating said stoker, and means including a thermostat controlled by the temperature of the space to be heated for automatically adjusting said stoker to a high rate of feed when the thermostat demands heat and automatically adjusting said stoker to a low rate of feed when the thermostat is satisfied, a normally opened switch in said motor circuit, mean operated by said thermostat controlled means for closing said switch when said thermostat demands heat, a second switch in said motor circuit in parallel to said first switch, a timing mechanism, and means operated by said timing mechanism for periodically closing said second switch for predeterminedintervals of time, said timing mechanism and means operated thereby including a synchronous electric motor, a speed, reducing gear train driven thereby, means for shifting said gear train to obtain different speed reductions, and adjustable cam means driven by said gear train for regulating the periods of closing of said second switch, thereby intermittently operating said stoker motor at said low rate of feed when said thermostat is satisfied.

FRED H. GLEASON. EDWARD C. AVERY. 

